U.S. Pat. No. 2,818,899 proposes a sealant gun that contains a gas cartridge in its grip part. Once the cartridge is opened, the compressed gas of the gas cartridge presses a plunger within a cartridge in the direction of the cartridge head. The flow of the pasty mass is controlled by a central rod that extends through the cartridge and can close the outlet opening of the cartridge.
U.S. Pat. No. 3,938,709 (1976) describes a dispensing device in which gas pressure is used to squeeze out a tube that is situated inside the hollow gun body. In this context, the gas flow is attained through a simple pin valve having a spring that can be actuated through a manual lever. A device for discharge of the gas was not provided. This means that the gun continues to press on the material due to the existing residual pressure despite the gas feed being interrupted.
EP 0 169 533 A2 (1985) discloses an injection device for viscous substances. In this device, the squeezing process does not continue after the supply of compressed gas is interrupted, because an injection control valve that interrupts the flow of viscous substance is situated at the outlet opening. What is interesting in this context is that the valve of the trigger grip can be used to control both the supply of gas and, simultaneously, the exit of the viscous substance. The injection control valve closes when there is no application of compressed gas.
A similar system is described in U.S. Pat. No. 4,925,061. However, in this system the injection control valve is actuated through a rod that is connected to the trigger grip.
A gun for squeezing out bone cement is disclosed in EP 1 118 313 A1. The propulsion is effected through a gas cartridge in this case also. What is essential is that this very complex system includes a rod that serves the purpose to expel the residual amount of cement contained in the dispensing tube. This elegant technical solution is very well-suited for conventional poly-methyl-methacrylate bone cements. However, said gun cannot be used for cartridge systems for mixing multiple components with a static mixer. Moreover, the manufacture of said gun is very elaborate.
US 2004/0074927 A1 describes an applicator gun which discloses essentially the same features as U.S. Pat. No. 4,925,061.
Printed publications US 2005/0230433 A1, US 2005/0247740 A1, and U.S. Pat. No. 6,935,541 B1 propose basically the same technical solution that is known already from EP 0 169 533 A2.
WO 2008/109439 A1 discloses a compressed gas-operated dispensing device that uses a hydraulic medium onto which the compressed gas presses.
It should be noted that the dispensing devices known to date, which are propelled by gas cartridges and have a complex mechanical structure, are suitable for manufacture as single-use articles only to a limited extent or not at all. Especially the valves proposed thus far are very expensive and thus make the use of the dispensing devices as single-use articles questionable. Moreover, the proposed technical solutions are difficult to implement in the form of plastic injection moulding parts.